Using Lexicon or Alphabet Cards, I've seen a magician have a spectator eliminate several cards in separate batches, at a time, only to have a few cards remaining. Those cards remaining then spell the spectator' name. At the beginning of this routine, the spectator is shown that all the cards have different letters. However, the end of the routine shows the first name of the spectator. Now where can I find a source that teaches these types of routines?